This invention relates generally to a machine for automatically driving threaded fasteners such as screws into a workpiece. More particularly, the invention relates to a machine of the type which includes a driving gun with a power-rotated screwdriver, a finder associated with the driver, and mechanism for transferring screws one at a time from a pick-up station to a delivery station where the screw is placed in the finder preparatory to being driven. The finder of such a machine keeps the screw in alignment with the driver and enables the driver to move into driving engagement with the head of the screw.
Automatic machines of the foregoing type are disclosed in my U.S. Pat. Nos. 3,279,045 and 3,675,302. In these machines, the driving gun is mounted on a supporting bracket and is automatically reciprocated toward and away from the workpiece to effect driving of the screws. In another type of automatic machine, the driving gun is held in the hand of the operator and is manually moved toward and away from the workpiece in order to drive the screw. A very widely used hand-held gun is of the semi-automatic type in which the screws are not fed automatically to the finder but instead are manually started into the workpiece and then are driven home by the power-rotated driver. Such a gun includes a comparatively simple tubular finder which is telescoped over the driver and which is urged to and normally disposed in an extended position so as to telescope over the head of the screw. During driving of the screw, the screw head presses against the finder and moves the latter to a retracted position along the driver. When the driver is released from the driven screw, the finder automatically returns to its extended position preparatory to telescoping over the next screw.